Method for commercial preparation of preferred isomeric forms of ester free conjugated fatty acids with solvents systems containing polyether alcohol solvents

ABSTRACT

Methods for sequential saponification and quantitative isomerization of glyceride oils containing interrupted double bond systems, with alkali in a polyether alcohol solvent to yield soaps with conjugated double bond systems are disclosed. The novel properties of the polyether alcohols allow the removal of water added with the alkali by boiling. The preferred embodiment uses a vegetable oil rich in linoleic acid such as sunflower or safflower oil, potassium hydroxide, phosphoric acid to neutralize the soaps. The reaction forms equal quantities of 9Z,11E-octadecadienoic acid and 10E,12Z-octadecadienoic acids.

BACKGROUND OF THE INVENTION AND CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Application No.60/175,631 filed Jan. 12, 2000.

This application is related to U.S. patent application Ser. No.09/451,710 filed Dec. 1, 1999 by Martin J. T. Reaney et al, thedisclosure of which is incorporated herein by reference.

FIELD OF INVENTION

This invention relates to an improved process for preparation ofconjugated fatty acids from materials rich in fatty acids containinginterrupted diene, triene and polyene systems. In a preferred embodimentthe reaction produces approximately equal amounts of the conjugatedlinoleic acid isomers 9Z,11E-octadecadienoic acid and10E,12Z-octadecadienoic acid from linoleic acid. The reaction is uniquein that the reaction proceeds rapidly at temperatures as low as 90° C.The process by-product stream is usable directly as a fertilizer thatlimits waste disposal costs.

Interrupted dienes moieties of fatty acids and esters thereof may beconverted to conjugated dienes, and higher polymers may also beconjugated. For examples, literature reports the synthesis of conjugatedforms of linoleic acid, linolenic acid and arachidonic acid using alkalicatalysts. Of the conjugated fatty acids that have been prepared,conjugated forms of linoleic acid are the most investigated. Conjugatedlinoleic acid or CLA is the trivial name given to a series of eighteencarbon diene fatty acids with conjugated double bonds. Applications of,and uses for, conjugated linoleic acids vary from treatment of medicalconditions such as anorexia (U.S. Pat. No. 5,430,066) and low immunity(U.S. Pat. No. 5,674,901) to applications in the field of dietetics,where CLA has been reported to reduce body fat (U.S. Pat. No. 5,554,646)and to inclusion in cosmetic formulae (U.S. Pat. No. 4,393,043).

Conjugated fatty acids, specifically CLA shows similar activity inveterinary applications. In addition, CLA has proven effective inreducing valgus and varus deformity in poultry (U.S. Pat. No.5,760,083), and attenuating allergic responses (U.S. Pat. No.5,585,400). CLA has also been reported to increase feed conversionefficiency in animals (U.S. Pat. No. 5,428,072). CLA-containing bait canreduce the fertility of scavenger bird species such as crows and magpies(U.S. Pat. No. 5,504,114).

Industrial applications for conjugated fatty acids also exist where theymay be used as lubricant constituents (U.S. Pat. No. 4,376,711).Conjugation can be used as a means to chemically modify fatty acids,such as linoleic acid, so that they are readily reactive to Diels-Alderreagents (U.S. Pat. No. 5,053,534). In one method linoleic acid wasseparated from oleic acid by first conjugation then reaction with maleicanhydride followed by distillation (U.S. Pat. No. 5,194,640).

Conjugated fatty acids occur naturally in ruminant depot fats. Thepredominant form of conjugated fatty acid in ruminant fat is the9Z,11E-octadecadienoic acid which is synthesized from linoleic acid inthe rumen by micro-organisms like Butryvibrio fibrisolvens. The level ofCLA found in ruminant fat is in part a function of dietary9Z,12Z-octadecadienoic acid and the level of CLA in ruminant milk anddepot fat may be increased marginally by feeding linoleic acid (U.S.Pat. No. 5,770,247).

Conjugated fatty acids may also be prepared by any of several analyticaland preparative methods. Pariza and Ha pasteurized a mixture of butteroil and whey protein at 85° C. for 5 minutes and noted elevated levelsof CLA in the oil (U.S. Pat. No. 5,070,104). CLA produced by thismechanism is predominantly a mixture of 9Z,11E-octadecadienoic acid and10E,12Z-octadecadienoic acid.

Conjugated fatty acids have also been produced by the reaction of soapswith strong alkali bases in molten soaps, alcohol, and ethylene glycolmonomethyl ether (U.S. Pat. Nos. 2,389,260; 2,242,230 & 2,343,644).These reactions are inefficient, as they require the multiple steps offormation of the fatty acid followed by production of soap from thefatty acids, and subsequently increasing the temperature to isomerizethe linoleic soap. The conjugated fatty acid product is generated byacidification with a strong acid (sulfuric or hydrochloric acid) andrepeatedly washing the product with brine or CaCl₂. Iwata et al. (U.S.Pat. No. 5,986,116) overcame the need for an intermediate step ofpreparation of fatty acids by reacting oils directly with alkalicatalyst in a solvent of propylene glycol under low water or anhydrousconditions. Reaney et al., in U.S. patent application Ser. No.09/451/710, entitled “Commercial production of CLA”, and Yurawecz,Mossaba, Kramer, Pariza and Nelson Eds. Advances in conjugated linoleicacid research, Vol. 1 pp.39-54 identified that conjugated fatty acidproducts prepared in the presence of glycol and other alcohols maytransesterify with fatty esters and produce esters of the glycol. Suchesters have been identified by Reaney et al. (unpublished data) incommercial products and in CLA prepared in propylene glycol by themethod of U.S. Pat. No. 5,986,116. Esters of CLA containing fatty acidsand propylene glycol have biological activity and therefore theirpresence in the CLA product is undesirable.

Conjugated fatty acids have been synthesized from fatty acids using SO₂in the presence of a sub-stoichiometric amount of soap forming base(U.S. Pat. No. 4,381,264). The reaction of linoleic acid with thiscatalyst produced predominantly the all trans configuration of CLA.

Efficient synthesis of 9Z,11E-octadecadienoic from ricinoleic acid hasbeen achieved (Russian Patent 2,021,252). This synthesis, althoughefficient, uses expensive elimination reagents such as1,8-diazobicyclo-(5,4,0)-undecene. For most applications the cost of theelimination reagent increases the production cost beyond the level atwhich commercial production of CLA is economically viable.

Of these methods, alkali isomerization of soaps is the least expensiveprocess for bulk preparation of conjugated fatty acids. However, the useof either monohydric or polyhydric alcohols in alkali isomerization ofconjugated fatty acids can be problematic. Lower alcohols are readilyremoved from the conjugated product but they require the productionfacility be built to support the use of flammable solvents. Highermolecular weight alcohols and polyhydric alcohols are considerably moredifficult to remove from the product and residual levels of thesealcohols (e.g. ethylene glycol) may not be acceptable in the conjugatedproduct.

Water may be used in place of alcohols in the conjugation of fatty acidsby alkali isomerization of soaps (U.S. Pat. Nos. 2,350,583 and4,164,505). When water is used for this reaction it is necessary toperform the reaction in a pressure vessel whether in a batch (U.S. Pat.No. 2,350,583) or continuous mode of operation (U.S. Pat. No.4,164,505). The process for synthesis of conjugated fatty acids fromsoaps dissolved in water still requires a complex series of reactionsteps. Bradley and Richardson (Industrial and Engineering ChemistryFebruary 1942 vol. 34 no.2 237-242) were able to produce conjugatedfatty acids directly from soybean triglycerides by mixing sodiumhydroxide, water and oil in a pressure vessel. Their method eliminatedthe need to synthesize fatty acids and then form soaps prior to theisomerization reaction. However, they reported that they were able toproduce oil with up to 40 percent CLA. Quantitative conversion of thelinoleic acid in soybean oil to CLA would have produced a fatty acidmixture with approximately 54 percent CLA.

Commercial conjugated linoleic acid often contains a mixture ofpositional isomers that may include 8E,10Z-octadecadienoic acid,9Z,11E-octadecadienoic acid, 10E,12Z-octadecadienoic acid, and11Z,13E-octadecadienoic acid (Christie, W. W., G. Dobson, and F. D.Gunstone, (1997) Isomers in commercial samples of conjugated linoleicacid. J. Am. Oil Chem. Soc. 74,11,1231).

The present invention describes a method of production of conjugatedfatty acids using a polyether alcohol, such as polyethylene glycol aloneor with a co-solvent as a reaction medium and vegetable oil, a fattyacid or ester thereof containing one or more interrupted diene moieties.In a preferred embodiment the reaction products of linoleic acid inpolyether glycol containing solvent are primarily 9Z,11E-octadecadienoicacid and 10E,12Z-octadecadienoic acid in equal amounts. The reactionproduct is readily released by acidification.

SUMMARY OF THE INVENTION

In the present invention the quantitative production of conjugated fattyacids from fatty acids and esters containing interrupted dienes orhigher polymers is achieved by heating the oil in a polyether alcoholwith an alkali base. As it is normal for small amounts of water to bepresent in the reaction materials this water may either be boiled fromthe reaction mixture by addition of heat or reaction must be performedin a pressurized vessel; thereafter, the reaction mixture is neutralizedby a strong acid, with solutions of H3PO4 being preferred. Surprisingly.when polyethylene glycol (PEG), and other polyether alcohols, are usedas a solvent, the boiling reaction mixture does not foam uncontrollably.Surprisingly, the PEG solvent allows the reaction to proceed rapidly attemperatures as low as 90° C. The selection of H₃PO₄ as the acid and KOHas the base allow the resultant salt solution to be disposed of insurface applications as a liquid or solid fertilizer. The reactionminimizes the production of undesirable isomers.

Thus, by one aspect of the invention there is provided a process forproducing a preferred isomeric mix of a conjugated linoleic acid-richfatty acid mixture comprising reacting a linoleic acid-rich oil with abase in the presence of a catalytic amount of said base, in a polyetheralcohol solvent containing medium, at a temperature above 90° C., andseparating said conjugated linoleic acid-rich fatty acid mixture fromsaid solvent by the addition of acid. In a preferred embodiment, 300 MWpolyethylene glycol is the preferred polyether alcohol.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is the gas liquid chromatogram of CLA prepared in water at 210°C. for 4 h;

FIG. 2 is the gas liquid chromatogram of CLA prepared in PEG at 130° C.for 4 h;

FIG. 3 is the gas liquid chromatogram of conjugated fatty acids preparedby treating flax oil in PEG at 130° C. for 4 h; and

FIG. 4 is the 1H nuclear magnetic resonance spectrum of the conjugatedfatty acids prepared by treating flax oil and KOH in PEG at 130° C. for4 h;

DETAILED DESCRIPTION OF THE INVENTION

The disclosed process quantitatively converts interrupted diene moietiesor higher interrupted polymers occurring in vegetable oils, fatty acidand esters of fatty acids to conjugated dienes or polymers withconjugated double bond moieties respectively. The process involvesblending said fatty acid or ester thereof with 1-6 moles of base, partof which acts as a reactant and part of which acts as a catalyst,dissolved in a polyether alcohol and 1 to 100 moles of water per mole ofhydrolysable acyl groups. The vegetable oil, fatty acids and esters mayinclude cottonseed, cucumber, grape seed, corn, safflower, soybean,sunflower or walnut oil or any other oil, wax or ester that is rich ininterrupted diene moieties or borage oil, flax oil or any other oil, waxor ester that is rich in interrupted polyene moieties. The reaction willproceed if about 1 mole of a base such as sodium metal, sodiumhydroxide, sodium alkoxylate, sodium carbonate, sodium bicarbonate,potassium metal, potassium hydroxide, potassium carbonate, potassiumbicarbonate or potassium alkoxylate is used as reactant and up to 5moles are used as the catalyst. The least expensive alkali that does notrepresent a disposal problem is potassium hydroxide. Furthermore,metallic alkali produces explosive hydrogen gas when added to water andmetal alkoxylates are flammable. These factors support the use ofpotassium hydroxide as the preferred catalyst/reactant. The reactionproceeds at temperatures above 90° C. and accelerates with increases intemperature. The comparatively low reaction temperature achieved inpolyethylene glycol is surprising as the reaction in a solventcontaining ethylene glycol, the parent molecule, is 20 fold slower underthe same conditions. We have found that the polyether alcohols aresuperior solvents to glycols. It is surprising that the conversion ofvegetable oil to CLA may be performed in as little as 1 part ofpolyether alcohol solvent per 2 parts of interrupted fatty acid or esterthereof. Preferred embodiments involve performing the reaction above130° C. It is a unique characteristic of this reaction that water in thereaction boils easily without foaming and it is not necessary to confinethe reaction in a sealed pressure vessel.

The reaction proceeds very rapidly at temperatures above 130° C. and issensitive to small changes in temperature. The reaction vessel used forthe process must have a homogeneous temperature or the reaction will notproceed uniformly. Homogeneous temperature is achieved by stirring orturbulent flow conditions. In a preferred embodiment the reactionmixture is prepared with a sub-stoichiometric level of KOH and heated tothe reaction temperature. The reactor is then charged with additionalcatalyst to begin the reaction. Using this method the reaction starts inthe time required adding the catalyst. The reaction is terminated eitherthrough addition of acid or through the rapid cooling of the reactionmixture to prevent the further formation of positional isomers.

After the reaction is complete the mixture is cooled to 90-100° C. forseparation of the reaction by-products. Acid is added to the reactionmixture to hydrolyze the soaps in the reactor. It is preferred to bringthe pH of the contents of the reactor to pH 4 or less through theaddition of either a mineral or organic acid. Acids that may be usedinclude, but are not limited to, hydrochloric acid, sulfuric acid,phosphoric acid, carbonic and citric acid, it is found that the use ofsulfuric and hydrochloric acid is problematic in that these strong acidsmay react chemically with the conjugated fatty acid during separation.The preferred embodiment of this invention involves the use ofphosphoric acid or citric acid to hydrolyze the soaps. When phosphoricacid is used the waste solution can be neutralized and used as a surfaceapplied fertilizer and there are no disposal costs for discarding thisproduct.

Poly ethers have some solubility in the fatty acid phase. We have foundthat polyethylene glycol 300 (PEG) accumulated to a concentration ofbetween 1 and 7 percent in the fatty acid phase during separation. Thisrelatively high concentration of polyether alcohol could not beeffectively removed from the fatty acids by water washing or washingwith brine. However, we have discovered that the polyether alcohol couldbe removed from the fatty acid layer by washing the fatty acids with 70percent aqueous phosphoric acid at between 85 and 110° C. We found thatthe emulsion breaking properties and phase partitioning properties ofpolyether alcohol molecules of widely different molecular sizes (PEG 300and PEG 8,000, having molecular weights of 300 g/mole and 8000 g/molerespectively) to be similar.

Reaction progress was determined by gas liquid chromatography. FIG. 1 isthe chromatogram of the product of reaction of sunflower with KOH inwater and FIG. 2 is a chromatogram of the reaction of sunflower oil withKOH in PEG. As may be concluded from FIGS. 1 and 2, the reaction inwater produces different isomers than the reaction in PEG. The reactionin PEG produces primarily the preferred 9Z,11E-octadecadienoic acid and10E,12Z-octadecadienoic acid isomeric mixture.

From examination of FIG. 3 it is apparent that the signal normallyassociated with the methylene group between the two olefinic groups thatshould occur near 2.6 ppm is absent. It is also apparent that signalsassociated with conjugated diene systems in the 5.3 to 6.3 ppm regionare now present. The absence of one signal with the concomitantappearance of the other signal is evidence that conjugation has beenachieved. FIG. 4 indicates that there are the two expected peaksassociated with conjugated linoleic acid, similar to FIG. 2, and a majorapparent single peak at 28.3 minutes representing the conjugatedlinolenic acids.

EXAMPLES Example 1

Sequential Hydrolysis and Isomerization of One Part Safflower Oil to CLAin One Part PEG 300.

To 600 g of PEG 300 were added commercial safflower oil (590 g) andaqueous KOH (45% w/w, 299 mL). The resulting reaction mixture was heatedat 140° C. for 2 hours in a two liter beaker with vigorous agitation.During heating vigorous boiling occurred, as water was lost from thesystem. After cooling to 100° C., the reaction mixture was acidifiedwith H₃PO₄ (85%, 222 ml).

The resulting mixture was heated for 0.5 h at 95° C. After standing for0.5 hours at 95° C., the top CLA layer was removed, washed with H₃PO₄(60%, 222 mL) at 95° C. for 30 minutes to remove excess PEG and water.The dried CLA layer was removed. The CLA product contained less than0.1% water and less than 0.0125% PEG as determined by the method of Muiret al. (Muir, A., A. Aubin and M. J. T. Reaney 1998, “Determination ofpolyethylene glycol (PEG 300) in long chain free fatty acid mixtures byreverse phase high performance liquid chromatography”, Journal ofChromatography A 810:241-244). The quantitative conversion of linoleicacid to CLA was confirmed by gas chromatography as described above.Under these reaction conditions most of the linoleic acid had reacted toform conjugated linoleic acids. Of the 74.2% linoleic acid in thestarting material a total of 6.2% remained unreacted in the finalproduct. Complete conversion of linoleic acid was achieved by longerreaction times not shown here.

TABLE 1 Fatty acid composition of CLA containing lipids derived fromsafflower oil. Fatty acid Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Palmitic acid7.66 7.21 7.41 7.32 7.15 7.57 Stearic Acid 2.43 2.40 2.41 2.40 2.32 2.36Oleic acid 16.01 15.75 15.73 15.70 15.26 15.94 Linoleic acid 6.17 13.042.27 4.00 65.54 3.48 9Z,11E-octa- 31.41 28.30 33.73 32.52 4.12 31.83decadienoic acid 10E,12Z-octa- 32.21 30.47 35.10 34.41 4.24 35.21decadienoic acid 9E,11E-octa- 1.88 1.73 1.95 2.04 <0.5 2.13 decadienoicacid 10E,12E-octa- 1.52 1.08 1.39 1.60 <0.5 1.44 decadienoic acid Ex 7Ex 8 Ex 11 Ex 12 Palmitic acid 7.41 7.54 7.21 7.02 Stearic Acid 2.362.49 2.59 2.57 Oleic acid 15.65 16.27 8.61 8.89 Linoleic acid 33.70 1.767.38 1.49 9Z,11E-octa- 18.82 33.02 33.78 37.42 decadienoic acid10E,12Z-octa- 19.56 34.46 36.84 39.21 decadienoic acid 9E,11E-octa- 1.342.09 2.37 2.11 decadienoic acid 10E,12E-octa- 1.13 2.36 1.21 1.26decadienoic acid

Example 2

Sequential Hydrolysis and Isomerization of Two Parts Safflower Oil toCLA in One Part of PEG 300.

All conditions were similar to example 1 except that 300 g of PEG 300were added commercial safflower oil (590 g) and aqueous KOH (45% w/w,299 mL). The conversion of linoleic acid to CLA was confirmed by gaschromatography as described above. Under these reaction conditions mostof the linoleic acid had reacted to form conjugated linoleic acids. Ofthe 74.2% linoleic acid in the starting material a total of 13.0%remained unreacted in the final product. Complete conversion of linoleicacid was achieved by longer reaction times not shown here

Example 3

Sequential Hydrolysis and Isomerization of Safflower Oil to CLA in PEG200.

All conditions were similar to example 1 except that PEG 200 (molecularweight 200 g/mole) was substituted for PEG 300. The conversion oflinoleic acid to CLA was confirmed by gas chromatography as describedabove. Under these reaction conditions most of the linoleic acid hadreacted to form conjugated linoleic acids. Of the 74.2% linoleic acid inthe starting material a total of 2.3% remained unreacted in the finalproduct. Conversion of linoleic acid of linoleic acid to CLA could beconsidered to be complete for commercial purposes.

Example 4

Sequential Hydrolysis and Isomerization of Safflower Oil to CLA in PEG600.

All conditions were similar to example 1 except that PEG 600 wassubstituted for PEG 300. The conversion of linoleic acid to CLA wasconfirmed by gas chromatography as described above. Under these reactionconditions most of the linoleic acid had reacted to form conjugatedlinoleic acids. Of the 74.2% linoleic acid in the starting material atotal of 4.0% remained unreacted in the final product. Completeconversion of linoleic acid was achieved by longer reaction times notshown here

Example 5

Sequential Hydrolysis and Isomerization of Safflower Oil to CLA inPropylene Glycol.

All conditions were similar to example 1 except that propylene glycolwas substituted for PEG 300. The conversion of linoleic acid to CLA wasconfirmed by gas chromatography, as described above. Under thesereaction conditions very little of the linoleic acid had reacted to formconjugated linoleic acids. Of the 74.2% linoleic acid in the startingmaterial a total of 65.5% remained unreacted in the final product. Thisresult shows that propylene glycol is an inferior reaction solvent topolyether alcohols.

Example 6

Sequential Hydrolysis and Isomerization of Safflower oil to CLA in PEG300 in a Sealed Pressure Reactor.

To 300 g of PEG 300 were added commercial safflower oil (295 g) andaqueous KOH (45% w/w, 149.5 mL). The resulting reaction mixture washeated at 180° C. for 4 hours in a sealed high pressure reactor withvigorous agitation. During heating boiling could not occur as thereactor was sealed throughout the reaction. After cooling to 100° C.,the reaction mixture was removed and placed in a 2000 mL beaker andacidified with H₃PO₄ (60%, 222 ml). The resulting mixture was heated for0.5 h at 95° C. After standing for 0.5 hours at 95° C., the top CLAlayer was removed, washed with H₃PO₄ (60%, 222 mL) at 95° C. for 30minutes to remove excess PEG and water. The dried CLA layer was removed.The CLA product contained less than 0.1% water and less than 0.0125% PEGas determined by the method of Muir et al., 1998. The quantitativeconversion of linoleic acid to CLA was confirmed by gas chromatographyas described above.

Example 7

Sequential Hydrolysis and Isomerization of Safflower Oil to CLA in aMixture of PEG 300 and Propylene Glycol.

All conditions were similar to example 1 except that a mixture ofpropylene glycol and PEG 300 (1:1, w:w) was substituted for PEG 300alone. The conversion of over half of the linoleic acid to CLA wasconfirmed by gas chromatography as described above. Of the 74.2%linoleic acid in the starting material a total of 31.8% remainedunreacted in the final product. Comparison of this result to example 5shows that PEG 300 can readily accelerate the conversion of linoleicacid to CLA in other solvents.

Example 8

Refining CLA Enriched Fatty Acids

The fatty acids produced by all of the methods mentioned above have astraw yellow colour and contain some metal ions as determined byinductively coupled plasma spectrometry. The yellow colour detracts frommarketability and the metal ions may cause the material to be unstable.One thousand grams of fatty acid produced as described in example 1 washeated under vacuum in an agitated sealed vessel at 70° C. and 10 gramsof bleaching clay (Supreme 120 FF), was added. The mixture wascontinuously stirred and heated to 105° C., under vacuum, for 30minutes. When the temperature of the mixture had decreased to 60° C.,the vacuum was released. The mixture was then filtered through a Celitefilter bed. The refining treatment had no effect on the fatty acidcomposition of the CLA containing product but improved the colour to alighter yellow.

Example 9

Removal of PEG from CLA by Washing with Phosphoric Acid.

Polyethylene glycol 300 (5 g) was dissolved in 100 grams of CLA rich oilproduced as described in example 1 and the sample was heated and stirredin 50 mL water at 100° C. for 15 min. The PEG 300 content of upper CLAphase was determined by the method of Muir et al. 1998 (supra). It wasfound that substantial amounts of PEG were detectable in the CLA phase.The experiment was repeated in a similar manner except that the waterwas replaced with 50 mL of phosphoric acid and the mixture was stirredat 110° C. for 15 min. After the latter treatment PEG was not detectedin the upper CLA rich phase.

Example 10

Production of CLA in PEG 300 in a Continuous Reactor.

To 300 g of PEG 300 were added commercial safflower oil (295 g) andsolid KOH (74 g). The resulting reaction mixture was heated at 120° C.for 20 minutes in a one-liter beaker with vigorous agitation. Duringheating boiling occurred, as a small amount of water was lost from thesystem. After cooling to 60° C., the reaction mixture was pumped througha heated tubular reactor. The reaction temperature was adjusted toeither 170° C. or 180° C. and the rate of pumping was adjusted so thatthe reaction time was between 5 and 15 minutes. The conversion oflinoleic acid to CLA was confirmed by gas chromatography as describedabove (results shown in table 2). Under these reaction conditions longerretention times and higher temperatures increased the total conversion.One skilled in the art of reactor design could develop a reactor tocontinuously convert linoleic acid dissolved in alkali solutions toconjugated linoleic acid.

TABLE 2 Flow Rate (Temp° C.) 1.5 1.0 0.5 1.5 1.0 0.5 Fatty Acids (170)(170) (170) (180) (180) (180) Palmitic Acid 6.74 6.73 6.81 7.06 6.936.76 Stearic Acid 2.48 2.47 2.49 2.49 2.51 2.50 Oleic Acid 8.13 8.178.30 8.29 8.28 8.30 Linoleic Acid 76.24 68.77 61.03 69.79 60.21 43.949Z,11E-octa- 3.11 6.41 9.97 6.02 10.26 17.42 decadienoic acid10E,12Z-octa- 3.29 6.48 10.62 6.35 10.94 18.90 decadienoic acid9E,11E-octa- <0.5 0.60 0.77 <0.5 0.87 1.51 decadienoic acid10E,12E-octa- <0.5 <0.5 <0.5 <0.5 <0.5 0.68 decadienoic acid

Example 11

Sequential Hydrolysis and Isomerization of Safflower Oil to CLA inIsopropyl-idene-rac-Glycerol.

All conditions were similar to example 1 except that1,2-O-isopropyl-idene-rac-glycerol (a diether alcohol with a chemicalstructure that is very different from polyethylene glycol) wassubstituted for PEG 300 and the reaction temperature was elevated to150° C. The quantitative conversion of linoleic acid to CLA wasconfirmed by gas chromatography as described above.

Example 12

Production of CLA Using a Linoleic Acid Source >80%

All conditions were similar to example 1 except that a >80% linoleicacid source was substituted for safflower oil. The quantitativeconversion of linoleic acid to CLA was confirmed by gas chromatographyas described above.

Example 13

Commercial Scale Conversion of Safflower Oil to CLA in PEG 300

To 340 kg of PEG 300 was added solid KOH (80 kg). The resulting mixturewas heated at 130° C. for 2 hours in 1000 liter reaction vessel withvigorous agitation. To the heated PEG was added commercial safflower oil(335 kg) and the temperature was raised and maintain at 140° C. for 4hours with vigorous agitation. After cooling to 110° C., the reactionmixture was acidified with H₃PO₄ (75%, 220 kg). The resulting mixturewas agitated for 0.5 h at 110° C. After standing for 0.1 hours at 110°C., the bottom layer containing salts, glycerol, PEG, excess H₃PO₄ andother non-free fatty acid materials was removed. The CLA layer waswashed with H₃PO₄ (75%, 110 kg) and the CLA layer was separated. Theacid washing step was repeated one more time. The CLA was finallyvacuumed dried and filtered. The quantitative conversion of linoleicacid to CLA was confirmed by gas chromatography as described above.

Example 14

Commercial Scale Conversion of Sunflower Free Fatty Acids to CLA in PEG300

To 340 kg of PEG 300 was added solid KOH (80 kg). The resulting mixturewas heated at 130° C. for 2 hours in 1000 liter reaction vessel withvigorous agitation. To the heated PEG was added sunflower free fattyacid (335 kg) and the temperature was raised and maintain at 130° C. for4 hours with vigorous agitation. After cooling to 105° C., the reactionmixture was acidified with H₃PO₄ (75%, 220 kg). The resulting mixturewas agitated for 0.5 h at 110° C. After standing for 0.1 hours at 110°C. the top CLA layer was removed, washed with H₃PO₄ (75%, 110 kg) at105° C. for 30 minutes to remove excess PEG and water. The washing stepwas repeated one more time. The CLA was finally vacuumed dried andfiltered. The quantitative conversion of linoleic acid to CLA wasconfirmed by gas chromatography as described above.

Example 15

Sequential Hydrolysis and Isomerization Flax Oil to Conjugated TrieneFatty Acids in PEG 300.

To 600 g of PEG 300 were added commercial flax oil (590 g) and solid KOH(150 g). The resulting reaction mixture was heated at 130° C. for 4hours in a 2 liter beaker with vigorous agitation After cooling to 100°C., a 5 ml aliquot of the reaction mixture was removed, acidified withexcess H₃PO₄ (75%, 20 ml) and stirred at 100° C. for 15 minutes. Thelayers were allowed to separate and a sample of the top layer wasremoved for analysis. FIG. 3 shows the gas chromatographic profile ofthe isomerized product. FIG. 4 show the 1H nuclear magnetic resonancespectrum of the conjugated fatty acids prepared by heating flax oil andKOH in PEG at 130° C. for 4 h.

What is claimed is:
 1. A process for producing a conjugated fattyacid-rich mixture comprising: reacting a fatty acid rich oil thatcontains some fatty acids with moieties selected from interrupted diene,triene and polyene with a base, in the presence of a catalytic amount ofsaid base, in an medium containing a polyether glycol solvent at atemperature above 90° C., and separating said conjugated fatty acid-richfatty acid mixture from said polyether alcohol solvent by the additionof acid.
 2. A process as claimed in claim 1 wherein said medium alsocontains a co-solvent.
 3. A process as claimed in claim 1, wherein saidoil is a vegetable oil selected from the group consisting of cottonseed,cucumber, grapeseed, corn, safflower, soybean, sunflower, flax seed,borage and walnut oil.
 4. A process as claimed in claim 1, wherein saidbase is selected from the group consisting of sodium metal, sodiumhydroxide, sodium alkoxylate, sodium bicarbonate, sodium carbonate,potassium metal, potassium hydroxide, potassium bicarbonate, potassiumcarbonate and potassium alkoxylate.
 5. A process as claimed in claim 1including the step of cooling said reaction mixture to a temperature ofbetween about 90° and about 100° before said separating step.
 6. Aprocess as claimed in claim 1 wherein a pH of said cooled reactionmixture is reduced to less than pH
 4. 7. A process as claimed in claim1, wherein said acid is selected from the group consisting ofhydrochloric, sulfuric, phosphoric and citric acid.
 8. A process asclaimed in claim 1 wherein said temperature is in the range 130°-180° C.9. A process as claimed in claim 1 wherein said temperature is about140° C.
 10. A process, as claimed in claim 1, wherein the polyetheralcohol solvent is polyethylene glycol with a molecular weight of atleast 200 g/mole.
 11. A process as claimed in claim 1, wherein at least55% of said conjugated fatty acid produced comprises 9Z,11E-octadecadienoic acid and 10E, 12Z-octadecadienoic acid.
 12. Aprocess as claimed in claim 1, wherein the reaction produces similaramounts of 10E, 12Z-octadecadienoic acid and 9Z, 11E-octadecadienoicacid.
 13. A process as claimed in claim 2, wherein the polyether alcoholincludes water as a cosolvent.
 14. A process as claimed in claim 2,wherein the polyether alcohol includes an alcohol as a cosolvent.
 15. Aprocess as claimed in claim 2, wherein the polyether alcohol includespropylene glycol as a cosolvent.
 16. A process as claimed in claim 2,wherein the polyether alcohol includes glycerol as a cosolvent.
 17. Aprocess as claimed in claim 1, wherein the process is a continuousreaction.